1. Field of the Invention
The invention concerns a device for the integral joining of a metal block which can be made up of plates, by hard soldering or brazing, wherein the hard solder or braze provides in solder gaps located between adjacent segment plates a large surface area junction with minimal thickness.
2. Description of the Related Art
This type of device is known from DE 196 29 217 A1 in connection with a hydraulic valve, both for the housing as well as for the piston.
In the known device the solvent material as provided in depository spaces which are closed off after the segment plates have been assembled into the configuration into which the block is to be formed by brazing. The depository spaces are formed by aligned circular holes of the same diameter extending through adjacent contacting segment plates, the depository spaces being closed off on their ends by segment plates without holes. They must have relatively thick cross sections, in order to be able to take up sufficient soldering material. In general such solder depository spaces do not extend over the entire length of the plate device viewed perpendicular to the solder gaps, but only over several solder gaps, and there are multiple solder depository spaces provided offset over the length of the stack, so that overall all solder gaps can be provided with liquid solder.
It has been found, without taking into consideration of the fundamental suitability of the known device for producing surface xe2x80x9cwelded throughoutxe2x80x9d and therewith pressure resistant metal blocks, that a substantial investment is required in testing, in order to determine the size of the depository space and arrangement thereof within the metal blocks to be produced by brazing which, in a series production, results in a reproducible good quality, that is, results in a solder connection over the entire area of the contact surfaces. There is a further consideration that the blocks must be so orientated for the soldering process that the tubular shaped depository spaces must run exactly horizontally, so that the molten solder material distributes evenly over the length of the depository space and can reach the solder gaps, which must be respectively supplied via the solder depositories. The thus xe2x80x9cverticalxe2x80x9d orientation of the solder gaps or, as the case may be, segment plates which must be aligned along their narrow outer border surfaces, requires fixation means in order to securely hold the plates together in the orientation necessary for joining, before they are soldered to each other.
It is thus the task of the invention, of improving a device of the above described type in such a manner, that independent of the orientation of the solder gaps a large surface area brazing of adjacent segment plates of a multi-layer of metal block is reliably achievable over the entire common contact surface thereof and the device can be achieved with simple technical means.
This task is solved in accordance with the basic concept of the invention in that at least one capillary solder flow path is provided which starts at a solder depository containing a supply of brace material, which melts upon heating of the stack of plates, via which flow path the melted solder material flows directly to the individual capillary solder gaps provided between the facing surfaces of the segment plates.
In accordance therewith, the capillary effectxe2x80x94which makes the soldering possiblexe2x80x94is also used for the transport of solder material to the individual solder gaps and thereby makes it possible for the solder, obviously within the boundaries within which the capillary effect is effective, to practically simultaneously supply all the solder gaps in the sense of a xe2x80x9chydraulicxe2x80x9d parallel circuit and to provide an even supplyxe2x80x94respectively depending upon needxe2x80x94of solder material, in which capillaries the solder can then, again on the basis of the capillary effect, spread out and perfuse the segment plates over a large surface area. In the solder flow path liquid solder material continues to flow until the solder gaps of the metal block are filled and the capillary network formed by the flow path and the solder gapsxe2x80x94wherein high adhesive forces occur between the gap walls and the solvent materialxe2x80x94are filledxe2x80x94and at the same time xe2x80x9cfully wettedxe2x80x9dxe2x80x94, wherein it can be insured by the appropriate limitation of the available supply of solder material, that the large volume hollow spaces provided within the metal block are not filled, since on the basis of the capillary action in the very narrow gaps first only the xe2x80x9cnarrowxe2x80x9d solder gaps are filled, into which the solder material is evenly drawn, before a supplying or pooling of solder material can occur in other xe2x80x9cnon capillaryxe2x80x9d hollow spaces.
When employing the inventive device no exhaustive testing need be carried in order to determine an optimal arrangement of solder supply channels to enable the setting up of a series production; rather, it is sufficient to supply solder material in sufficient amount so that the solder gaps of the metal blocks inclusive of the solvent supply paths can be completely filled, which is easily possible using mathematics or a computer. The inventive device can be realized using simple designed, premanufactured parts with minimal technical investment.
Beginning with a rather conventional design of the metal block, in which the outer narrow surfaces of the segment plates are in alignment with each other, and with their large surface areas running coplanarxe2x80x94at least in areasxe2x80x94so that a capillary solder flow path can be provided in such surface areas, this can be realized in simple manner for example by means of a profile rod laid against the outside of the metal block, which profile rod crosses over the solder gaps of the metal block, for example with linear contact.
The solder flow paths located at the outer areas of a segment plate stack and running horizontal or vertical can be established by using a predefined design, and accordingly a reliable capillary effect be realized with simple means, in the manner that the segment plates are provided with edge open recesses which align with each other, the edge surfaces running perpendicular to the solder gaps and collectively forming a groove traversing the solder gaps, into which a profile rod is inserted, which borders or defines within the groove at least one acute narrowing closed-edged channel and is held in contact with or covering the groove wall along at least one line crossing the solder gap.
These solder supply paths according to the basic design can be realized in many diverse ways, for which the details, alternatives and specifications which can be used in combination are discussed below. Depending upon the shape of the groove there results therein, in combination with an at least segment-wise cylindrically shaped profile rod, either a contact line along which two wedge-like narrowing capillary gaps connect with each other with continuously narrowing gap (0) and disappearing wedge angle (0), this for example in a case that the cylindrically curved area of the profile rod comes into contact with a planar base surface of the groove, or two contact lines when the groove has a V-shaped cross section, or possibly even three contact lines when a profile rod with a cylindrical surface spanning more than 180xc2x0 in circumference is introduced in a groove, which has two groove walls parallel to each other, between which a planar groove base extends.
In the case that at least two contact lines result on the basis of the shape of the profile rod and the groove in which it is inserted, the closed edged channel formed by the profile rod and the groove is also suitable as solder depository space for wire or flat bar shaped brace, this in any case when the groove depth is relatively large, that is, in the case of right-angular joining groove boundary surfaces corresponding at least to the curvature radius of the cylinder outer surface of the rod inserted in the groove.
Alternatively to this, the solder supply paths provided outside on the segment plate stack for solder transport to the solder gaps can, according to the characteristics discussed below, also be realized with grooves of relatively shallow depth at the plate sides and with a corresponding basically flat rod shaped profile bodies, which by wedging into or bending over the groove can also confer a suitable pre-fixing of the segment plate stack for the welding process in a welding oven.
In order to provide suitable spaces for receiving solder supply central recesses can be provided within this type of xe2x80x9cflatxe2x80x9d grooves, which along the outer side are bridged over by a profile bar and thereby are closed off towards the outside. A solder supply path of this design is suitable at least in the case that these are formed running vertically, and/or are provided on vertically or diagonally rising outer surfaces of the metal block which for their part are at right angles or diagonal to the solvent gaps. Alternatively or additionally to a solder supply path running along the outer edge surface of the plate stack, an xe2x80x9cinnerxe2x80x9d, that is, a solder supply path bordered by the segment plates themselves, can be realized in the manner, that this is formed by preferably round closed edged openings in the block forming segment plates, the openings aligned with each other, and a profile rod extending through these openings, which profile rod has a shape geometrically similar to the shape of the opening and having a slightly smaller cross sectional area than the area of the opening, and which is in a continuous, line-forming contact with the edges of the openings of the segment plates. For this, a cylindrical rod can be suitable, which has a somewhat smaller diameter than the opening of the segment plates, and with respect to the central longitudinal axis of the opening is provided eccentrically, such that a continuous contact results along one line on the outer surface of the profile rod.
In a preferred design of the device at least one solder supply path is provided, which is formed by round-edged openings in the segment plates aligned with each other and a helical spring or coil extending through the channel formed by these openings, of which the spring coils are in continuous linear contact with each opening edge, wherein it is particularly preferred, when the helical spring is wound on a block, which corresponds to the smallest possible cross section of thexe2x80x94in this casexe2x80x94closed edged capillary solder transport channel.
When at least two solder supply paths are provided, for example in a diametrically opposed arrangement relative to the central axis of the segment plate stack, then these can be used for holding the segment plates in a defined positionxe2x80x94aligningxe2x80x94arrangement in the sense of a pre-fixing for the soldering process.
Independent of whether the capillary solder supply path is provided at the outer area of the metal block to be joined by brazing or in the internal area thereof, pocket or funnel shaped solder depository spaces for receiving a solder supply, in communication with the ambient atmosphere, can be provided in such a device, so that molten solder can flow under the influence of gravity to the capillary solder supply path(s).
Solder supply paths as described below are particularly suitable for the edge areas of a metal block comprised of multiple segment plates with right-angled edge areas, and can be produced by simple bending of tongue-shaped plate elements.
By means of a suitable tie rod or by a through-bolt introduced in the joined metal block, it is possible in simple manner to stabilize the metal block against expanding forces, which could result for example by the high hydraulic pressure of the connecting channels extending throughout the metal block.
When closedxe2x80x94xe2x80x9cblindxe2x80x9dxe2x80x94hollow spaces are provided in the segment plate stack, which are preferably defined by openings of identical cross-section aligned with each other in the xe2x80x9cintermediatexe2x80x9d segment plates sandwiched between the outermost segment plates, then it is possible in simple manner, as discussed below, to tightly press the segment plates to be joined with each other during the welding and to produce minimal solder gap widths, which result in particularly solid solder connections.